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K3 Rev C +AF filter

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Mike K4PI

K3 Rev C +AF filter

I am anxious to see what the new board will do. I have used QF1A for many
years and never found a radio yet where it did not enable me to copy signals
much better. I treat my QF1As like gold and never operate without one in
the Peak mode.
73 Mike K4PI

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Dick Dickinson

Re: K3 Rev C +AF filter

Does the DSP Board swap change anything other than the audio chain, and is
that for headphones only?

73,
Dick - KA5KKT

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Vic K2VCO

Re: K3 Rev C +AF filter

In reply to this post by Mike K4PI

k4pi wrote:
> I am anxious to see what the new board will do. I have used QF1A for many
> years and never found a radio yet where it did not enable me to copy signals
> much better. I treat my QF1As like gold and never operate without one in
> the Peak mode.

All the board changes do is improve low end response, which in my opinion is already more
than good enough for CW and SSB work.

The 'filter' mentioned is not a peak or null filter, but just a lowpass filter to remove
some very high-pitched DSP artifacts that bother some operators.

In my opinion, this replacement board is not something that everyone needs. I will
probably order the filter sub-board by itself when it becomes available even though I'm
probably too old to hear the DSP artifacts in question, but don't intend to bother with
replacing the DSP board.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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Corboy - Poteet

Re: K3 Rev C +AF filter

In reply to this post by Mike K4PI

David Olean

Re: K3 Rev C +AF filter

In reply to this post by Vic K2VCO

I have two K3s, one has the new DSP board, so I hooked them up together and
listened to low frequency tones. The higher SN radio definitely has more
bass. In fact I have noted a few times, just how low it goes. It seemed very
unusual for a communications radio to do that. So I listened to the older
one and it has less bass, but to be honest, I don't see a problem with it.
It sounds just fine to me. Now if it was my stereo FM receiver I would heave
it out, but I chase DX with it and see no big reason to update it. I guess
it is a personal decision for folks. I am using a Heil headset to make the
comparison. I am almost 65 years old and my hearing is hosed on the high
end. I am not sure if it is from the several decades of weak signal work, or
having way too much fun in the 60's, but my upper limit is now a bit over 6
or 8 kHz. I tune in CW at about 450-500 Hz.

Dave K1WHS

----- Original Message -----
From: "Vic K2VCO" <[hidden email]>
To: "k4pi" <[hidden email]>
Cc: <[hidden email]>
Sent: Thursday, December 17, 2009 9:43 PM
Subject: Re: [Elecraft] K3 Rev C +AF filter

> k4pi wrote:
>> I am anxious to see what the new board will do. I have used QF1A for
>> many
>> years and never found a radio yet where it did not enable me to copy
>> signals
>> much better. I treat my QF1As like gold and never operate without one in
>> the Peak mode.
>
> All the board changes do is improve low end response, which in my opinion
> is already more
> than good enough for CW and SSB work.
>
> The 'filter' mentioned is not a peak or null filter, but just a lowpass
> filter to remove
> some very high-pitched DSP artifacts that bother some operators.
>
> In my opinion, this replacement board is not something that everyone
> needs. I will
> probably order the filter sub-board by itself when it becomes available
> even though I'm
> probably too old to hear the DSP artifacts in question, but don't intend
> to bother with
> replacing the DSP board.
> --
> 73,
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

DaveL G3TJP

Re: K3 Rev C +AF filter

In reply to this post by Mike K4PI

I have one of the upgraded boards.

Mine is a rev B with some SMT component changes that achieves approximately the same result as W9AC's bass extension mods, although Elecraft seem not to have changed some of the capacitor values. I think I read somewhere they were achieving the same result with altered resistor values instead.

There is also a small PCB holding one IC and a handful of SMT components that connects to the main PCB by six through connections. I suspect there may be track cuts beneath it, but I've had no reason to investigate beneath the add-on PCB. Yes, by the time shipping and return carriage for the return board, it is indeed expensive for those on this side of the pond.

After fitting the upgraded Rev. B DSP board, I turned my K3 on without an antenna connection and had one of those heart-in-mouth moments, because there was just silence instead of the usual hiss. My RF gain was still set to fully clockwise and my AF gain was set to around 9 o'clock, but there was no hiss. After a couple of deep breaths, a few checks showed the K3 to be working, QUIETLY!

So, in summary, I have a Rev B board with no sticker to indicate it's a Rev. C board. It has been upgraded with component changes to improve bass response and has a a small active LPF added to reduce hiss and high frequency artefacts. Both mods do their jobs well in my opinion.

As I'm not afraid to use a soldering iron on a piece of expensive kit, had the LPF add-on board been available I would undoubtedly have fitted that myself, together with the W9AC mods. The add-on PCB would survive the mail in a small Jiffybag and there would be no requirement to return the unmodified DSP board, but YMMV and in my case it serves to remind me that hindsight remains the only exact science.

I have already fitted the W9AC mods mods. to a friend's DSP board and it works as well as Elecraft's mods for enhanced LF audio. If the LPF becomes available as an add-in kit, I shall most certainly fit one to my friend's K3 and hopefully it will save him a shower of bucks.

To those contemplating W9AC's mods, watch out. The two 100uF 10v SMT electrolytics he specifies are 6.3mm diameter and are intended to replace two 10uF components that are 5mm in diameter on a PCB designed to take 5mm SMTs. I was unhappy with the cosmetics of fitting the larger electrolytics and eventually settled on using two SMT 100uF/10v tantalums, which fitted very nicely. I note on the modified DSP board that Elecraft have used two 100uF 6.3v electrolytics, which are 5mm diameter, so with hindsight, I'd have fitted those instead of the tants, which were some order of magnitude more expensive than the electrolytics.

73 and Season's Greetings to all.

DaveL G3TJP

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srife

Re: K3 Rev C +AF filter

In reply to this post by David Olean

Sorry, my posts have been going to individuals instead of the reflector.

I have tinnitus in both ears and less high frequency noise is a good
thing for me. I can see where the younger guys, and some older ones that
still have good hearing, are not bothered by the K3 audio. The Heil headset
does seem to make an improvement...or maybe it's just that all of the other
noises (room etc.) go away and it makes listening to the K3 much better
because you can turn down the AF gain some.

I'll have to admit that I have not attempted adjustment to the
equalizers or messed with the AGC adjustments that some have mentioned. I am
in the process of getting SN/0690 up-to-date with the mods that are listed
on Elecrafts site, and also have ordered the upgraded DSP board. Once the
hardware & FW are up to date I'll start digging in the new manual and see if
I can make my listening experience better.

This is a good thread and I'm listening.

Stan Rife
W5EWA

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of David Olean
Sent: Thursday, December 17, 2009 5:01 PM
To: Vic K2VCO; k4pi
Cc: [hidden email]
Subject: Re: [Elecraft] K3 Rev C +AF filter

I have two K3s, one has the new DSP board, so I hooked them up together and

listened to low frequency tones. The higher SN radio definitely has more
bass. In fact I have noted a few times, just how low it goes. It seemed very

unusual for a communications radio to do that. So I listened to the older
one and it has less bass, but to be honest, I don't see a problem with it.
It sounds just fine to me. Now if it was my stereo FM receiver I would heave

it out, but I chase DX with it and see no big reason to update it. I guess
it is a personal decision for folks. I am using a Heil headset to make the
comparison. I am almost 65 years old and my hearing is hosed on the high
end. I am not sure if it is from the several decades of weak signal work, or

having way too much fun in the 60's, but my upper limit is now a bit over 6
or 8 kHz. I tune in CW at about 450-500 Hz.

Dave K1WHS

----- Original Message -----
From: "Vic K2VCO" <[hidden email]>
To: "k4pi" <[hidden email]>
Cc: <[hidden email]>
Sent: Thursday, December 17, 2009 9:43 PM
Subject: Re: [Elecraft] K3 Rev C +AF filter

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